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D; W. BROWN.

APPARATUS FOR RECEIVING HERTZIAN WAVES.

, I APPLICATION FILED MAY 26. 1917- 1,319,989.

2 SHEETS-SHEET l.

Patented Oct. 28, 1919.

75 oscillaior D. W. BROWN.

APPARATUS FOR RECEIVING HERTZIAN WAVES.

APPLICATION FILED MAY 26. 1917.

Patented Oct. 28,1919.

2 SHEETS-SHEET 2 either case, the result mwm w. Brown, or NEW max, is. Y. nuance non nncmvme nnnrznm waves.-

' Specification of Letters Patent.

Patented Oct. 28, 1919.

Application filed May 20, 1917. Serial m. mince.

To all whom/it may concern:

Be it knownthat I, DAVID W. BnowN, a citizen of the United States, and a resident of the borough of Manhattan, in the'city,

5 county, and State of New York, have invented certain new and useful Improvements in Apparatus for Receiving Hertzian Waves, of which the following is a speclfication.

This invention relates to improvements in apparatus for receiving Hertzian waves. In systems for receiving and utilizing Hertzian Waves sent from distant transmitting, or oscillating, apparatus, and of which L5 systems of wireless telegraphy are examples,

the energy of the high frequency electric oscillations set up by the Hertzian waves in the receiving system is so small, that, un

less the efiect of said oscillations upon the detectors is increased, said detectors will not be properly operated by the oscillations, and consequently the distance between the sending and the receiving stations is limited.

5 'It is the object of the, present invention to'so reinforce said oscillations, or increase the effect thereof on the detectors at the, a receiving station, that wireless telegraphlc and other systems .for utilizing Hertzian 0 waves at receiving stations can be successfully' and regularly operated over distances between the sending and receiving stations greater than is now practicable.

This invention proceeds upon the follow- 5' ing principles: Whenever an electric current flows along a wire, there is developed a field of electro-magnetic force all around said. wire. The nature of electricity remains the same in its various forms, whether of D constant electricity, low frequency alternat ing currents, or high frequency oscillating currents such as are used in wireless telegraphy. Therefore, constant current f of electricitv is caused 5 to flow through a field which is produced by high frequency oscillations, or when a high frequency oscillations are caused to vibrate through a field which is produced by constant current electricity, then, in is an algebraic strengthening of the electrical gurrent, either the constant current or the high frequency oscillations. By algebraic strengthening .of the electric current, I mean, for example, L that supposing that the independent curwhen an independent lations,

rent is field thereby developed around the aerial will increase'the strength of those vibrations of the high frequency oscillations which are in the positive direction, and will decrease the strength of those high frequency oscillations which are in the negat ve direction, and the effect of said oscillations Wlll be, in the total, increased upon the detecting instruments which are exposed to the action of said high frequency oscillations. Therefore, if high frequency oscilpositive in its direction, then the lations are caused to travel along an aerial,

along which constant currents are passing and developing a field of force around said aerial, then,vas said high frequency oscillatlons vibrate through said field of electromagnetic force, their strength will be in some manner algebraically increased, and their effects upon detecting instruments will be greater than they would have been had not the constant current been caused to flow along the aerial on which vibrate the high frequency oscillations before reaching the detecting instruments. In this present invention I cause a continuous flow of constant current electricity to proceed along a certain part of the aerial wire which provides the path for the high frequency oscillations, when said high frequency oscillations are produced on the antenna by Hertzian waves which come from a distant sending station. This constant current, being c0ntinuous,'is always flowing on the aerial, and therefore there is always produced, and is always existing=a constant field of electromagnetic energy around the aerial, into which come and through which flow the high frequency oscillations. 'Now, as said high frequency oscillations flow through the existing and continuous field of electromagnetic energy which is ,produced around the aerial, said high frequency oscillations are, in effect, magnified, or there is produced an algebraic total of the effect of both the elec-' tromagnetic energy produced by the constant current and the high frequencyosciland said total effect is a greater upon the detecting instruments than the effect of the high frequency oscillations alone would have been. Therefore, my invention results in magnifying the effect of'the high frequency oscillations beyond what their effect would have been, as received from the distant sending station if they had not been,

so to say, Strengthened by the additionof I the constant current electricity to the aerlal.

struments, if said constant currentwere per-' mitted to reach the detecting instrument, said constant 'current must be prevented from reaching the detecting instrument, although said constant current must continue to flow along some part of the aer1al so as to always produce the constant independent field of electromagnetic force. Now I prevent said constant current from reachin the detecting instruments and improperly a ecting them when the high frequency oscillations are not coming along on the aerial, by interposing resistances which said constant current cannot pass through between the geneIatOr of said constant current and the detectors. Such a resistance to the passage of constant current is a condenser, as is well known, and I also may use ahigh non-inductive resistance between the generator of the constant current and said detecting instruments.

Thus this invention provides, on the one hand, for continuously supplying a current of electricity to some part of the aerial along which travel the high frequency elec tric oscillations on their way to the detectors,

' and on the other hand I interpose resistances between the generator of said constant current and the detectors, which prevent the passage of said constant currents to the detectors when the high frequency oscillations are not traveling on said aerials. When said high frequency oscillations are traveling on the aerial, the total effect of the constant current and the high frequency oscillations is some algebraic total, or some function, of the strength of both the constant current electricity and the high frequency oscillations, and said high frequency oscillations, being thus strengthened, and, as is well understood, not being prevented from reaching the detectors by the condensers or the non-inductive resistances, flow freely across the condensers, or through said non-inductive resistances, with their strength much increased over what their strength would have been had the constant. current'not have been caused to flow along the aerial.

The foregoing explanation will make it clear that although the detector is'not in that art of the aerial which is affected by the IIIdGPBIIdGIlbCOIlStMIt 'current,-yet it is operated by the high frequency oscillations, for

said high frequency oscillations travel along the whole extent of the aerial, not being checked by the condenser or other high noninductive resistances; and therefore said high frequency oscillations reach and affect the detector. Said explanation will also make it plain that the resistances, that is,

either the condenser or the high inductive resistances, do prevent the independent constant current from reaching the detector; or, as I explain it, said condenser or said hi h inductive resistances do insulate the tector from the independent constant current, so that said independent constant current does not affect the detector when the high frequency oscillations are not traveling on the aerial. But, in that case, saidindependent constant current simply fiows round and round on its parts of the aerial which is connected with the independent generator, and through said connectin wires and generator, and continues to ow round and round in its own independent circuit while said high frequency oscillations are not being received on-the aerial. When said high frequency oscillations are being received on the aerial, they flow through the field of force that has been developed around the aerial by said independent constant current, and are strengthened thereby. Said high frequency oscillations of course maintain the same frequency of vibration or alternation that they had before entering said field. The effect of said field which is produced by said'constant current is to algebraically add to the strength of the high frequency oscillations, and give to said high frequency oscillations a power to influence the detector, that is greater than such high frequency oscillations, as received from the distant sending station, would have had had the independent constant current not been applied to the aerial and generated the independent field of electromagnetic force around said aerial.

The invention further contemplates that condensers may be so operatively connected wlth said aerials that said independent currents will normally maintain said condensers in charged condition; and said invention also contemplates the further increase of the strength of said independent field by the use of small intensifying conductive sheaths -or tu bes inclosing or practically inclosing said aerials, but insulated therefrom. Said sheaths or tubes may 'be constructed and 'arranged in various ways, and among them'in the manner termed sometimes herein a compound aerial, and said sheaths may either be charged or not, by electric currents ingependent of said high frequency oscilla- 1ons.

Said detectors are represented in the accompanymg drawlngs as cohere'rs, but they may be of any type. Referring to said-drawings which illustrate various modifications of the invention in a diagrammatic manner, Figure 1 is a diagrammatic representation ofone modification of the invention, wherein the detector is directl coupled, or closely coupled, with the aerial Fig. 2 represents diagrammatically another modification wherein the detector is directly coupled Wlth the aerial; Fig. 3 is a diagrammatical representation of an inductively coupled system; Fig. 4 is a diagrammatical representation of an inductively coupled s stem with intensifying sheathsor tubes, an Fig. 5 is a cross section on larger scale, of a tube and aerial; Fig. 6 diagrammatically represents an inductively coupled system with a compound aerial; Fig. 7 is a broken elevation showing an intensifying tube composed of sections and Fig. 8 is a broken aerial an independent V develops and maintains about said aerial a field of electromagnetic energy, which field is independent of the high frerfilenlcIy oscil lations set up on said aerial B y ertzian waves received from the sending station.

' current supplie Said source of electricity G is represented in the several figures ofth drawings as an electric battery, but may be any suitable generator of'electricity. When such oscillations arrive on said aerial B, the effect of saidindependent field is, so to say, to reinforce said oscillations or increase their effect on the detector D, which is electrically connected with said aerial B, either by direct coupling, as in Fig. 1, or by inductive coupling through a transformer, 3 and certain other figures.

I preferto provide choke coils k, k in said circuit g, g to prevent high frequency oscillations passing along said wires 9, g, and I also prefer'to provide a variable resistance R to regulate the strength of the independent current delivered to said aerial B. If it is desired to utilize said aerial B, both for sending and for receiving oscillations, a switch S of any suitable design may 'be provided; said switch S being indicated in Fig. 1 and other figures in the position for receiving oscillations from the antenna,

and indicating a contact and circuit for placing the oscillator, not shown,'-in circuit with said aerial, the detector and other apparatus of the local receiving circuit being then cut out.

To electricall separate or insulate the d to said aerial Bfrom, and,

prevent its improperly affecting the detector, -(for.said current is so strong, as above stated,that it would otherwise improperly operate the detector), I provide suitable separatin or insulatin devices, preferably a variabl condenser between said detector as in Fig.

D and said aerial B, and the independent current supplied to said aerial B will preferably' be a constant current.

The operation of the system set forth in Fig. '1, of the drawings is as follows: Assume that there are no Hertzian waves coming from the distant station, there will then, nevertheless, be a continuous' current from the independent generator G flowing along the aerial BB and in the circuit gg. This current will generate a field of electro-magnetic force around said aerial B-B in that part of the said aerial which is between the connections of the wires g-g" with said aerial. This current will, however, not be able to reach or injuriously affect the detector D, because of the condenser C, or other suitable'resistance, which said constant current cannot traverse. Said constant current will, therefore, flow round and round in its independent circuit,'being regulated by the variable resistance R, and being able to traverse the choke coils k, which practically interpose no resistance to the flow of the constant current. Thus the condition now is, thatthere is now constantly maintained a field of electro-mag netic force immediately around that part of the aerial BB through which said constant current is flowing; but this force cannot affect the detector. Now suppose that Hertzian waves arrive on the antenna A from the distant sending station. Those Hertzian waves set up a high frequency oscillation on the antenna, which high frequency oscillations readily pass through the condenser A and flow along said aerial BB, and through tor. It will be seen that these high frequency oscillations have to as through the constantly maintained field of electromagnetic force on their way from the antenna A to the detector high frequency oscillations pass through said constantly maintained field, (which is around the said aerial B-B that forms the pathfor said high frequency oscillations), they absorb, as.1t were, energy from said constantly maintained field, and are, so to say, revivified, so that they act on the detector more energetically than they would have done had'the not been so revivified.

I may arrange t e condenser C in series with the aerial B and the independent circuit wire 9, as indicated in Fig. 2, so that thesaid constant generator circuit will become charged up to that limit at which the counter-electro-motive force of said ,con-

denser 0 becomes as great as the electrosaid condenser C to the detec- I D. Now as said i aerial B- -B, there will be von sai electric potential equal to that of said counthrough said field and through motive force of the current from said generator G. Then, provided no high frequency oscillations are traveling on said aerialian ter electro-motive force. Now, when the high frequency electric oscillations 1pass along t e condensers CC on their way to the detector D,

. oscillations flow through said condensers and ata inc osing, as great a length as is practicable induce the discharge across them of someor mor of said accumulative electric motive forc In this arrangement of apparatus I prefer to place a second condenser C, or-

other suitable insulating device, between said condenser C and the detector, and to connect the wire 9 with the aerial wire B oint between said condensers.C-.C. Re erring to Fig. 3, which shows the detector'D inductively coupled with said aerial B through a transformer T--T, a condenser C, preferably variable, is now operativel connected with said aerial B between t e connection with said circuit wire 9 and the transformer -TT. The operation of this form of the invention will be readily understood from the foregoing description of the construction and operation of the apparatus of Fig. 1.

Referring to Figs. 4 and '5, and noting that intenslfying sheaths or tubes H, which are more specifically the subject of my other application for United States Letters Patent, granted August 7, 1917, .No. 1,235,650, may be applied as well to a direct coupled as to an inductively coupled s stem, H is a small metallic tube, prefer abl of copper, inclosing or substantially of said aerial B, but insulated from said aerial. The diameter of said tube H should be the smallest practicable to allow for adequate insulation from said aerial B. Saidinsulating material may be of any suitable kind, and I prefer insulating disks h, h, Fi 5, secured at such intervals in said tube as to prevent all contact of said aerial B with. said tube H, said aerial passing axially through said disks. I also prefer to provide openings through said disks, as notches in the edges, to permit circulation of air 'to diminish the tendency of saidtube H to heat. An insulatin cap, as 7', may be placed .over the upper en of said tube H- to keep out moisture. Such small conductive tubes, which I sometimes term intensifiersv, or intensifying tubes, exercise an influence to intensify any oscillations vibrating on said aerial B; and I may further increase this effeet by connecting said tube H by insulated wires 'Z-Z, with an independent electric .current (preferably. a constant current) 74 from any suitable generator of electricity, sov that an electric current continually flows along said tube H; but said tube H may be used without such current.

The generator of the current for said 71 to said aerial B; and I pre er to so arran e 8' the c1rcu1t wire connections with said tu H, that the direction of current along said tube H will be the same as that along said aerial B. I also prefer to provide choke coils lck', at proper positions to prevent 8 the high frequency osci lations from reaching said tube H (see Figs. 4 and 5); and when said tube H is connected with a separator generator G (Fig. 4) I also prefer to provide a separate variable resistance R. 9

The operation of this form of the invention will be readily understood with but little further explanation. Assumin that the independent current with which said tube H is charged is flowing in the same direction 9 as the independent current on said aerial BB, then the combined effect of the parallel currents, which are flowing both. on said aerial B+-B, and in said tube H, will be to generate a strong field of electro-mag- 1 netic force within said tube H and around said aerial 'B-B. Now, .when Hertzian waves arrive on the antenna A, and high frequency oscillations travel on said aerial B--B, the effect of said high frequency 05- 1 cillations on said detector D will be correspondingly increased.

In Figs 4 and 5 said intensifier sheath is shown as a small tube H,'inclosing the aerial wire B, but these intensifier sheaths may be 1 also constructed as coils of insulated wire P, coiled around said aerial B, the whole forming what I term a compound aerial, and as indicated in Fig. 6. When such a compound aerial is used, I prefer to con- 1 nect the ends of said coil P with their own independent electric generator G, and with choke coils k7c and variable resistance- R, though, of course, said coil P might be connected with the same generator G as 1 supplies the independent current to said aerial B. Said coil P will surround as great a length of aerial B as is practicable, and will act as an intensifying sheath, the

compound aerial being of convenient con- 1 .structlon for transportation and erection at any station. The operation of the apparatus *will be plain from the foregoing explanations.

Said intensifier tubes may be made in sec- 1 pieces B joined together at the ends tional lengths H, placed end to end and around the aerial wire, which may also be in y electrically conductive couplings X, (Fig. 7). To insure good insulation of said tubes H from said wires B at points adjacent to said couplings X, insulating disksh are placed around said wires B between the ends of said couplings X and said tubesections H; and it is also advisable to place other insulating disks it inside of and adjacent to eachend of said tube sections H. The ends of adjacent tube sections H are electricall connected by conductive sleeves or strips secured to the adjacent ends of said tube sections. The said insulating disks h and k may be very conveniently constructed by winding adhesive non-conducting tape, of any suitable width, around the said aerial wire B or B, at desired points, so aS to form plugs or disks of a size to fit within said tubes B or B theadhesiveness of the tape cementing 'it suf ficiently firmly to said aerial wire, and also holding the successive windings of the tape together. In this way the aerial, with its tube, may be readily assembled at the site where the aerial is to be erected.

To facilitate supporting the aerial and its tube on the aerial supporting frames or masts, the said sections H of said tube may be provided with supporting shoulders n. Certain of said shoulders n rest on insulating blocks or strapsy which are fastened to the supporting frame W, as indicated in Fig. 7 A cross sectional view of saidstrap y, and of the sheath and the insulating disks is indicated in Fig. 8.

The said intensifier tubes may in some cases be conveniently formed in halves, with longitudinal flanges .to secure the halves together around the aerial wire B or B, as indicated in Fig. 9, and the insulating disks may also be formed in halves h and secured in any suitable manner in said half tubes H.

It willbe understood that the usual instruments, such as relay telephone or other instruments,-will be provided in the local circuit of the detector, which local circuit is indicated in Figs. 1, 2, 3, 4 and 6 by the wires t-t'.

It will be well to place a condenser A" between. the antenna A and the connection of the independent circuit wire 9 with said aerial B, as indicated in Fig. 1 and certain other figures, to diminish possible leakage of the independent current from said antenna tips.

When plugs of adhesive non-conducting tape are used, as hereinbefore suggested, said plugs may have a loose fit in the intensifier tubes H or H, so as to ermit of circulation of air in said tubes i desired. Said caps j may also be located so as to leave an annular aperture between the said caps and the upper ends of said intensifier tubes for the same purpose.

aerial of greater strength than sufiicient to operate said detector, and a condenser between said detector and the connection of said current with said aerial.

3. The combination in a system for receiving high frequency electric oscillations, of an aerial, a detector operatively connected therewith, an independent generator of current of more than sufiicient strength to operate said detector, a circuit connecting said current with said aerial, a condenser to prevent said current reaching said detector, and'chbke coils preventing high frequency oscillations from passing into said circuit.

4. The combination in a system for receiving high frequency electric oscillations of a receiving aerial, a shunt circuit connected therewith, and. an independent electric generator in said shunt circuit adapted to continuously maintain a current in said shunt circuit and a part of the aerial, and choke coils and a variable resistance in said shunt circuit.

Signed at New York cit New York, and State 0 25th day of May,

in the county of New York, this A. D. 1917.

DAVID W. BROWN. Witnesses:

WILLIAM PATIEI/ISON, WALTER N. HARRIS. 

